Field of the Invention
The present invention generally relates to digital image signal processing circuits, and more particularly, is directed to improvements in a digital image signal processing circuit which is used in an image pickup and recording apparatus, in which a first operating condition for recording on a record medium a video signal obtained from an image pickup output signal obtained from an image pickup device on and a second operating condition for recording a video signal supplied from the outside a record medium are selectively set up, so as to perform various kinds of digital processing to the video signal obtained from the output signal of the image pickup device or the video signal supplied from the outside.
There has been proposed an image pickup and recording apparatus which corresponds to both of a video camera operative to perform image pickup operation to obtain an image pickup output signal and to produce a video signal based on the image pickup output signal and a video tape recorder operative to record a video signal on a magnetic tape, incorporated with each other, and comprises a camera portion functioning as the video camera and a recorder portion functioning as the video tape recorder. Such an image pickup and recording apparatus has been put to practical use as a so-called video tape recorder incorporated with a video camera (hereinafter, referred to as a VTR with camera).
In the VTR with camera which works with a color video signal, a first operating condition in which the camera portion thereof is operative to produce the color video signal containing a luminance signal and a carrier chrominance signal based on an image pickup output signal obtained through an image pickup operation and the recorder portion is operative to produce a recording luminance signal and a recording carrier chrominance signal by processing the luminance signal and the carrier chrominance signal constituting the color video signal produced by the camera portion to be suited for recording and further operative to record the recording luminance and recording carrier chrominance signals on a magnetic tape, and a second operating condition in which a color video signal containing a luminance signal and a carrier chrominance signal is supplied from the outside to an external input terminal provided to the recorder portion and the recorder portion is operative to produce the recording luminance signal and the recording carrier chrominance signal by processing the luminance signal and the carrier chrominance signal constituting the color video signal supplied from the outside to be suited for recording and further operative to record the recording luminance and carrier chrominance signals on the magnetic tape, are selectively set up.
The VTR with camera working with the color video signal in the manner mentioned above is required to have a signal processing circuit for producing the color video signal based on the image pickup output signal in the camera portion (hereinafter, referred to as a camera signal processing circuit) and another signal processing circuit for producing the recording luminance and recording carrier chrominance signals based on the luminance and carrier chrominance signals constituting the color video signal in the recorder portion (hereinafter, referred to as a recorder signal processing circuit). In the previously proposed VTR with camera working with the color video signal, the camera signal processing circuit and the recorder signal processing circuit are independently designed to be exclusively used in the camera portion and the recorder portion, respectively. For example, the camera signal processing circuit is formed in several integrated circuit chips mounted on a first printed wiring board to be used in the camera portion and the recorder signal processing circuit is formed another several integrated circuit chips mounted on a second printed wiring board to be used in the recorder portion.
Each of the camera signal processing circuit and the recorder signal processing circuit which are independently provided in the VTR with camera as mentioned above comprises a plurality of circuit sections each taking charge of respective signal processing. The camera signal processing circuit contains usually selected circuit sections in no small numbers, each of which is common or compatible in function with a corresponding selected one of circuit sections contained in the recorder signal processing circuit. These selected circuit sections contained in the camera signal processing circuit and the recorder signal processing circuit, respectively, to correspond to each other perform substantially the same signal processing operation or respective signal processing operations bearing a close resemblance to each other. Especially, in the case where each of the camera signal processing circuit and the recorder signal processing circuit is formed into a digital circuit in which major signal processings are digitalized, the camera signal processing circuit and the recorder signal processing circuit contain, in addition to the selected circuit sections as mentioned above, respective circuit sections corresponding to each other which perform different kinds of signal processing operations, respectively, but handle digital signals having substantially the same bit rate or respective bit rates very close to each other, so as to have respective filter characteristics very close to each other and therefore each of which can perform both of the different kinds of signal processing operations selectively.
Under such circumstances, the signal processing circuit system in the previously proposed VTR with camera in which the camera signal processing circuit and the recorder signal processing circuit are independently provided and therefore a complicated circuit structure using a large number of circuit elements is employed so that production cost is increased and power consumption is relatively large, is desired to be improved by simplifying the whole construction.